JPS60129954A - magneto-optical disk recorder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a disk recorder using a magneto-optical disk that has features such as large capacity, high density, rewritability, and high speed access, and is useful for storing external memories and documents for convenience store storage, for example. It can also be used for image files, digital audio recorders, etc.

Conventional Structure and Problems There is shown in FIG. 1 a partially enlarged view of a conventionally used disk having a tracking guide and an address signal or synchronization signal. Figure 1a is a radial cross-sectional view of the disk;
1 is a disk substrate, 2 is a trunking guide (information writing part), 3 is a recording medium, and a laser beam 4 is incident as shown in the figure. FIG. 1 is a plan view of FIG. 1a, and 5 is a preformat signal such as an address signal or a synchronization signal that is previously formed on the tracking guide. FIG. 1C is a sectional view taken along the line AA in FIG.

FIG. 2 shows an example of a preformatted disc, where 9.6 is a preformatted synchronization signal, and 6 is a recording portion. FIG. 3 is a diagram showing how the disk shown in FIG. 2 is reproduced in a state where no signal is recorded, and the preformat signal 5 is suppressed every time the disk remains rotated. The recordable portion of the information signal is shown in FIG. As shown above, it is possible to record only the portion excluding the preformat signal 6.

However, this conventional disk has the disadvantage that the amount of information that can be written by the user is substantially reduced.Object of the InventionThe present invention provides for increasing the recording capacity of pregrouped and preformatted magneto-optical disks with a simple construction. aim to achieve.

Structure of the Invention The present invention provides a polarizing prism that irradiates information recorded thermomagnetically on a pre-grouped and pre-formatted magneto-optical disk with a laser beam and separates the reflected light into two polarized beams orthogonal to each other; an optical head that uses two photodetectors iW that receive polarized light, and a differential amplifier that takes the difference between the electrical signals detected by the two photodetectors, and a summing amplifier that takes the sum. This is a magneto-optical disk recorder featuring:

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention is shown in FIG. 4. In FIG. 4, light emitted from a semiconductor laser 8 is made into parallel light by a collimating lens 9, and passes through half mirrors 1o and 11 to an objective lens 12. This forms a light spot on the disk 13. Disk 13 is a magneto-optical disk that is pre-grouped and matted. A magnet 14 generates a bias magnetic field necessary for recording and erasing information signals. The reflected light from the disk 13 is a half mirror.
It is reflected by 1◯, passes through cylindrical lenses 21 and 22, and enters the multi-segment photodetector 23, where focus and tracking error signals are detected. Half mirror 11
The reflected light is polarized by a polarizing prism 15 such as a Rochon prism or a Wollaston prism, so that the light is polarized at right angles to each other.
The light is separated into two polarized lights, which pass through a convex lens 16 and enter photodetectors 1γ and 18, respectively, where they are converted into electrical signals. The polarizing prism 15 is rotated by 46 degrees around the optical axis with respect to the polarization direction of the reflected light from the half mirror 11.The light detected by the photodetectors 17 and 18 was originally detected by the head amplifier 19.
20 converts it into an electrical signal, and by taking the difference in the differential amplifier 24, it is possible to detect the photothermomagnetic recorded signal, and by taking the sum in the adding amplifier 26, preformat signals such as address signals and synchronization signals can be detected. can do.

The above-mentioned situation is shown in FIG. FIG. 5a shows a portion of one track, where numeral 5 represents a trunk, numeral 5 represents a preformat signal, and numeral 26 represents an information signal recorded photothermally and magnetically. Consider the case where the light spot of the optical system shown in FIG. 4 scans over the trunk A. Figures 5 and 5C show the levels of electrical signals converted by the head amplifiers 19 and 2O shown in Figure 4, and the broken lines in the figure indicate the levels of the electrical signals converted by the head amplifiers 19 and 2O shown in Figure 4.
Figure B shows the reproduced waveform when there is no information signal bit 26, that is, when photothermal magnetic recording is not performed, and both of these waveforms have the same phase and the same level. When the information signal bit 26 exists in FIG. 6a, the output of the head amplifiers 19 and 20 shown in FIG. 4 has a reproduced waveform as shown by the solid lines shown in FIGS. 6b and 6c. The reproduced waveforms based on the information signal bit 26 have opposite phases to each other in FIG. 6C.

6d is a signal obtained by taking the difference between the signals shown in FIG. 5 and c, that is, the output signal of the differential amplifier 24 in FIG. 4. The in-phase preformat signals are canceled by taking the difference, and the reproduced signal of information signal bit 26, which is in opposite phase, is doubled, and a stable information signal as shown in FIG. 5d can be obtained. .

FIG. 6e is a signal obtained by taking the sum of the signals shown in FIG. 5 and c, that is, the output signal of the summing amplifier 26 in FIG. At this time, the reproduced signals of information signal bits 26, which are in opposite phases, cancel each other out, and the 7' IJ format signals, which are in phase, are expanded twice to obtain a stable preformat signal as shown in Figure 6e. be able to.

Effects of the Invention By implementing the present invention, it is possible to perform photothermal magnetic recording also on preformat signal bits and to separate both signals easily and with high precision.

By developing the present invention, for example, in permanent recording disks such as compact disks, a recording material having a magneto-optical effect can be used instead of vapor-deposited aluminum on the light-reflecting surface. By doing so, it is possible to record signals as RAM on top of ROM using the principle described above, and it becomes possible to detect both signals independently, thereby doubling the recording density per several disks at most. It is possible to increase it to. Therefore, if the present invention is applied to a Type 4 data recorder, the ROM and RAM can be realized in a single disk, and various applications can be expected.

[Brief explanation of drawings]

Fig. 1 is a partially enlarged view of a disc having a conventionally used tracking guide and address signal or synchronization signal, Fig. 2 is a diagram showing an example of a preformatted disc, and Fig. 3 is the disc shown in Fig. 2. FIG. 4 is a system block diagram showing an embodiment of the present invention, and FIG. 6 is a diagram showing how the same signal is reproduced. DESCRIPTION OF SYMBOLS 1... Disc substrate, 2... Tracking guide, 3... Recording medium, 4... Laser beam, 5... Preformat signal, 6
... Recording part, 8 ... Semiconductor laser,
9...Collimating lens, 10°11...
... Half mirror 112 ... Objective lens, 13
...Disc, 14...Magnet,
16...Polarizing prism, 16...Convex lens, 1γ, 18...Photodetector, 19.20...
...Head amplifier, 21.22...Cylindrical lens, 23...Multi-division photodetector, 2
4... Differential amplifier, 26... Adding amplifier, 26... Information signal bit. Name of agent: Attorney Toshio Nakao and 1 other person 1st
Figure 4 Figure 2 Figure 3

Claims (1)

[Claims] A recording medium having a magneto-optical effect is spun or vacuum-deposited on a disk substrate having a tracking guide in the form of a concentric or spiral mechanical groove, and on which an address signal, etc. is partially recorded in uneven form. Using a magneto-optical disk, a semiconductor laser, a collimating lens, a half-mirror-9 objective lens, etc., and two orthogonal beams of reflected light from the magneto-optical disk, which have been recorded thermomagnetically, are used.
an optical head composed of a polarizing prism that separates light into two polarized lights, two photodetectors or one two-split photodetector that receives each of the two polarized lights, and an electrical signal detected by the two photodetectors. A magneto-optical disk recorder comprising a differential amplifier that takes the difference between the two electrical signals, and a summing amplifier that adds the two electrical signals.